For the dough: 

1. In a large bowl, mix the flour and the salt. Add the butter cubes and mix with a potato masher, hands, or two knives until the butter is incorporated but you can still see pea-sized chunks of butter.
2. Add the water and mix until a dough begins to form. 
3. Roll your dough into a 5 by 10-inch rectangle. Fold one side of your dough 2/3 of the way across. Fold the other side of your dough across to make an “envelope.” Turn your dough one quarter of the way around, then repeat the process of rolling, folding, and turning two more times. Wrap your dough in plastic wrap and chill it in the refrigerator for two hours or in the freezer for an hour.
4. Take your dough out and roll, fold, and turn it twice more.
5. Rip a sheet of parchment paper the size of your baking sheet and place it on the counter. On that piece of parchment, trace a 14-inch circle. Turn your parchment over so the dough won’t touch the pencil markings but you can still use them as a guide.
6. Take your dough out and place it on your parchment. Roll your dough out to match the 14-inch circle. Then, trim the edges of your dough into roughly a 12-inch circle. Place the parchment containing your dough on a baking sheet and then place the whole thing in the fridge to chill while you prepare the apples. 

For the tart: 

1. Preheat the oven to 400 degrees Fahrenheit. Peel and core five medium green apples. Cut them in half and then slice those halves as thin as you can. Take out your dough, and arrange the apples in circles, starting from the edges and moving inward. Brush the apples with melted butter. 
2. Bake the tart for 25 to 30 minutes, or until the edges of the tart and the apples start browning. Cool for five minutes, then brush the tart with apricot jam.